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Old 18th November 2009, 11:00   #1
John Bantin
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Heart attack?

On reading over reports of casualties that occur during diving, I'm tempted to ask: Why do CCR divers appear to be more predisposed to heart-attacks in the water than those on OC?
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Old 18th November 2009, 11:12   #2
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Re: Heart attack?

When he breaths higher level of CO2 , I guess...
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Old 18th November 2009, 11:13   #3
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Re: Heart attack?

Hi John,

I'm no expert on this, but have been watching the emerging discussion over the last year or so. It's worth searching on here for posts by Alex Deas on the subject. I think Simon Mitchell has been involved too. That should give you a starting point on the various reasons that people have put forward.

HTH,
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Old 18th November 2009, 11:17   #4
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Re: Heart attack?

Maybe because they are older, fatter lazier and richer?
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Old 18th November 2009, 11:28   #5
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Re: Heart attack?

Quote: (Originally Posted by John Bantin) View Original Post
On reading over reports of casualties that occur during diving, I'm tempted to ask: Why do CCR divers appear to be more predisposed to heart-attacks in the water than those on OC?
Trolling today John?

I suspect Heart attack is sometimes used in "reports" as a coverall for- We don't know much about rebreather diving and SCUBA equipment, we're just coroners!

However the older, fatter, richer, lazier, high CO2, stressed arguments all carry weight too IMO
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Old 18th November 2009, 11:56   #6
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Re: Heart attack?

Quote: (Originally Posted by Ben Field) View Original Post
Trolling today John?
Not trolling - unless you confuse food-for-thought with ground-bait!
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Old 18th November 2009, 12:04   #7
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Re: Heart attack?

Quote: (Originally Posted by John Bantin) View Original Post
On reading over reports of casualties that occur during diving, I'm tempted to ask: Why do CCR divers appear to be more predisposed to heart-attacks in the water than those on OC?

I beleive the issue is related to retained co2 more than anything else.

I cut and passte this as referance on the subject:



Exercise needs an amount of oxygen and the cells in turn produce an amount of C02. As cardiovascular rate increases blood flow and lung breathing rate and volume increases. This with the addition of stress and increased excitement this in turn releases stress hormones and adrenalin.

The rebreather all this time with the help of your lung power is pushing the expired C02 laden gas around the breathing tube, through the scrubber and through the loop. Work enough to be called work of breathing WOB. Increased C02 production levels relative to C02 elimination in the scrubber material stimulates the nervous system to increase heart rate, increasing blood volume and blood pressure. The diver is now experiencing the onset of Hypercapnia.

With continued high C02 loadings in the breathing bag then peripheral blood vessel dilation will occur. This will have the effect of increasing heart rate even further culminating in massive myocardial contractions or heart attack.

The second important point is the equipment examination. After a death (in the UK) the equipment (if recovered) is examined by an expert witness. Of most reports I have read, the equipment on examination has show normal operation, the gas analysis (if available) has also been normal within limits. The expert witness would therefore conclude that the equipment was working correctly at the time of death. So as the cause of death is on the coroner to conclude and with a normal autopsy this is routinely shown to be a heart attack. Remember a diver is only a diver while he is alive. At death he is classified as a corpse.

So conclude equipment tested and found to be working OK. Therefore cause of death heart attack. The reason and cause of the heart attack was C02 in the loop. Iain Middlebrook[/QUOTE]
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Old 18th November 2009, 12:08   #8
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Re: Heart attack?

Sorry buisy at work and cant find the link:

Also look into lactic acid production C02 and heart failure


ATB

Mark
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Old 18th November 2009, 12:18   #9
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Re: Heart attack?

Quote: (Originally Posted by Mark Chase) View Original Post
I beleive the issue is related to retained co2 more than anything else.

I cut and passte this as referance on the subject:



Exercise needs an amount of oxygen and the cells in turn produce an amount of C02. As cardiovascular rate increases blood flow and lung breathing rate and volume increases. This with the addition of stress and increased excitement this in turn releases stress hormones and adrenalin.

The rebreather all this time with the help of your lung power is pushing the expired C02 laden gas around the breathing tube, through the scrubber and through the loop. Work enough to be called work of breathing WOB. Increased C02 production levels relative to C02 elimination in the scrubber material stimulates the nervous system to increase heart rate, increasing blood volume and blood pressure. The diver is now experiencing the onset of Hypercapnia.

With continued high C02 loadings in the breathing bag then peripheral blood vessel dilation will occur. This will have the effect of increasing heart rate even further culminating in massive myocardial contractions or heart attack.

The second important point is the equipment examination. After a death (in the UK) the equipment (if recovered) is examined by an expert witness. Of most reports I have read, the equipment on examination has show normal operation, the gas analysis (if available) has also been normal within limits. The expert witness would therefore conclude that the equipment was working correctly at the time of death. So as the cause of death is on the coroner to conclude and with a normal autopsy this is routinely shown to be a heart attack. Remember a diver is only a diver while he is alive. At death he is classified as a corpse.

So conclude equipment tested and found to be working OK. Therefore cause of death heart attack. The reason and cause of the heart attack was C02 in the loop. Iain Middlebrook
[/quote]

oh mighty, I think Simon will jump in quickly

paul


from what I understand, at this moment, there is no scientific evidence of correlation between high CO2 (retained or inhaled) and increased risk of heart attack
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Old 18th November 2009, 12:22   #10
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Re: Heart attack?

Quote: (Originally Posted by John Bantin) View Original Post
Not trolling - unless you confuse food-for-thought with ground-bait!
I know John, hence the smilie.... (it is however treading a fine line IMO)

For years the report of "heart attack" has been the fuel for many flame-wars and long drawn out pointless threads as many protagonists feel it is the result of a null-result to any other test looking for COD in rebreather diving accidents.

Its certainly food-for-thought but as far as I'm aware there is no new data on this one, unless you have something?
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